Human Eosinophil Cell Manipulation by Optical Tweezers

Abstract

In this work, lateral deformation of human eosinophil cell during the lateral indentation by an optically trapped microbead of diameter 4.5 µm is studied. The images were captured using a CCD camera and the Boltzmann statistics method was used for force calibration. Using the Hertz model, we calculated and compared the elastic moduli resulting from the lateral force, showing that the differences are important and the force should be considered. Besides the lateral component, the setup also allows us to examine the lateral cell-bead interaction. The mean values of the properties obtained, in particular the elastic stiffness and the shear stiffness, were Eh = (37.76 ± 2.85) µN/m and Gh = (12.57 ± 0.32) µN/m. These results show that the lateral indentation can therefore be used as a routine method for cell study, because it enabled us to manipulate the cell without contact with the laser.